Title bars (any browser, any application) are not an issue with a proper window manager. For example, simply add the following to ~./jwmrc to remove the Opera title bar in JWM:
I used to build Firefox-PGO in the mozillaZine Forums, here are some I posted for Ubuntu users back in 2009 (links are dead): Downloads: Portable Minefield (Firefox) 3.0.10 PGO (w/o Java) Builds
. Suffice to say that I have a bit of experience with FF. And with Opera (since 2.x on Windows). Not so much with Chromium, though I am currently running a custom compile (not from ABS). That said, Opera is the definite speed king and not just across benchmarks. And it is highly customizable. FF is the most forgiving and compatible, yet the slowest, even with PGO and chrome heavily hacked. Chromium is right there in between.
In binary size and dep requirements, perhaps. Yet Opera consistently scores higher in every instance of every benchmark I run vs. the same version of Opera under Windows 7 Ultimate 64-bit. This is repeatable. Unless you are short on disk space and memory, I would not worry too much as performance > size. But as a previous post alluded to, Opera does have it quirks. Fortunately, most quirks have their workarounds, including the redraw issue mentioned before. Moreover, it provides rich usability once it is learned. It is a lot like Linux in that you have to hack away at config files to get the most out of it.
Again, Opera is highly customizable. You can basically have it take up as little, or as much space as you desire. I hacked the default theme to show menu/address/navigation toolbars as text-only with minimal padding. Or you can run fullscreen with a visible address bar. Or with a visible address bar + navigation toolbar. Anything, really. Like many of you, I run a highly optimized Arch box with lightweight apps compiled with aggressive flags. surf, Midori, I have literally tried them all. But when it comes down to native features + usability + performance, Opera is hard to beat. To me, that is